METHOD OF MANUFACTURING INKJET PRINTHEAD AND INKJET PRINTHEAD MANUFACTURED USING THE SAME
A method of manufacturing an inkjet printhead using a channel forming material, in which a glue layer to enhance an adhesive force between a substrate and a channel forming layer is not required.
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This application claims priority under 35 U.S.C. §119(a) from Korean Patent Application No. 10-2007-0095448, filed on Sep. 19, 2007, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present general inventive concept relates to a method of manufacturing an inkjet printhead and an inkjet printhead manufactured using the method, and more particularly, to a simple method of manufacturing an inkjet printhead using a channel forming material, in which a glue layer to enhance an adhesive force between a substrate and a channel forming layer is not required, and an inkjet printhead manufacturing using the method.
2. Description of the Related Art
Inkjet printheads eject tiny droplets of printing ink to a predetermined portion of a to-be-printed target sheet so as to produce a predetermined color image. Inkjet printheads can be categorized into thermally driven inkjet printheads and piezoelectric driven inkjet printheads according to an ejection mechanism of ink droplets employed. As for thermally driven inkjet printheads, ink droplets are ejected by an expansion force of bubbles formed when a heat source is applied to ink expand. With regards to piezoelectric driven inkjet printheads, ink droplets are ejected when a pressure generated by deformation of a piezoelectric device is applied to ink. However, thermally driven inkjet printheads and piezoelectric driven inkjet printheads are operated using the principle that ink droplets are ejected by a predetermined energy, and only a method of ejecting ink differs in the two above mentioned types of inkjet printheads.
Referring to
An ink droplet ejection mechanism of the conventional thermally driven inkjet printhead will now be described in detail. Ink is fed into the ink chamber 53 through the ink feed hole 51 and the restrictor 52. The ink filled into the ink chamber 53 is then heated by the heater 41 formed of a resistance heating material and located in the ink chamber 53. Once the ink boils, ink bubbles are formed, and the formed ink bubbles expand to generate pressure that is to be applied to the ink filled into the ink chamber 53. Therefore, the ink in the ink chamber 53 is ejected out of the ink chamber 53 through the nozzles 54 in a form of droplets.
US 2007/0017894 discloses a method of manufacturing an inkjet printhead; the method includes a flow path wall forming operation of forming flow path walls on a substrate having energy generating elements formed thereon, an imbedded material depositing operation of depositing an imbedded material between the flow path walls and on a top of each flow path wall, a flattening operation of polishing a top of the deposited imbedded material, until the top of the flow path wall is exposed, and a operation of forming an orifice plate on the tops of the polished imbedded material and the exposed flow path wall. However, when a liquid pathway forming element that is used to form ink channels and ink outlets is formed of a photoresist resin, a glue layer formed of a polyethylene amide resin is employed to enhance an adhesive force between the liquid pathway forming element and a silicon substrate.
Due to use of the glue layer, the method further includes coating a glue layer formed of a polyethylene amide resin on a substrate, forming channel walls on the glue layer positioned with respect to an energy generation device, and patterning the glue layer by etching the glue layer using the channel walls as a mask. The entire manufacturing process is complex and expensive.
SUMMARY OF THE INVENTIONThe present general inventive concept provides a simple method of manufacturing an inkjet printhead using an excellent channel forming material, in which a glue layer to enhance an adhesive force between a substrate and a channel forming layer is not used.
The present general inventive concept also provides an inkjet printhead manufactured using the method.
Additional aspects and utilities of the present general inventive concept will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the general inventive concept.
The foregoing and/or other aspects and utilities of the general inventive concept may be achieved by providing method of manufacturing an inkjet printhead, in which the method including forming a heater to heat ink, and an electrode to supply a current to the heater, on a substrate, forming a channel forming layer to define an ink channel by coating a first negative photoresist composition on the substrate on which the heater and the electrode are formed and then patterning the coated composition using a photolithography process, forming a sacrificial layer on the substrate on which the channel forming layer is formed such that the sacrificial layer covers the channel forming layer, planarizing top surfaces of the channel forming layer and sacrificial layer using a polishing process, forming a nozzle layer having a nozzle by coating a second negative photoresist composition on the channel forming layer and the sacrificial layer and patterning the coated composition using a photolithography process, forming an ink feed hole in the substrate, and removing the sacrificial layer, wherein each of the first and second negative photoresist compositions includes a prepolymer having a monomer repeating unit which has one of a glycidyl ether functional group, a glycidyl ether functional group and an oxythane functional group, and one of phenol novolac resin-based backbone, bisphenol-A-based backbone, bisphenol-F-based backbone, and alicyclic backbone, a cationic photo initiator, a solvent, and an adhesion promoter.
The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing an inkjet printhead including a substrate, and a channel forming layer directly formed on the substrate without a glue layer formed therebetween, wherein a negative photoresist composition having an adhesion promoter to improve an adhesive force of the channel forming layer with respect to the substrate is used to form the channel forming layer.
The foregoing and/or other aspects and utilities of the general inventive concept may also be achieved by providing a method of manufacturing an inkjet printhead, the method including forming a channel forming layer on a substrate to define an ink channel by coating a first negative photoresist composition on the substrate, and forming a nozzle layer having a nozzle by coating a second negative photoresist composition on the channel forming layer, wherein each of the first and second negative photoresist compositions includes an adhesive promoter so that a glue layer is not used between the substrate and the channel forming layer.
The above and other features and utilities of the present general inventive concept will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:
The present general inventive concept may be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the general inventive concept to those skilled in the art. In the drawings, the thicknesses of layers and regions are exaggerated for clarity. It will also be understood that when a layer is referred to as being “on” another layer or substrate, the layer can be directly on the other layer or substrate, or intervening layers may also be present.
Reference will now be made in detail to embodiments of the present general inventive concept, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain the present general inventive concept by referring to the figures.
Various embodiments of the present general inventive concept set forth herein will be described based on a thermally driven inkjet printhead. However, the present general inventive concept can also be applied to a piezoelectric driven inkjet printhead. Also, the present general inventive concept can be applied to a monolithic type of inkjet printhead and a contact type of inkjet printhead. The drawings of the present application illustrate only a part of a silicon wafer, and the inkjet printhead according to the present general inventive concept can be manufactured in a form of tens to hundreds of chips on a single wafer.
A method of manufacturing an inkjet printhead according to an embodiment of the present general inventive concept includes forming, on a substrate, a heater to heat ink, and an electrode to supply a current to the heater; forming a channel forming layer to define an ink channel by coating a first negative photoresist composition on the substrate on which the heater and the electrode are formed and then patterning the coated composition using a photolithography process; forming a sacrificial layer on the substrate on which the channel forming layer is formed such that the sacrificial layer covers the channel forming layer; planarizing top surfaces of the channel forming layer and the sacrificial layer using a polishing process; forming a nozzle layer having a nozzle by coating a second negative photoresist composition on the channel forming layer and the sacrificial layer and patterning the coated composition using a photolithography process; forming an ink feed hole in the substrate; and removing the sacrificial layer, wherein the first and second negative photoresist compositions may be the same or different from each other, and each of the first and second negative photoresist compositions includes a prepolymer having a monomer repeating unit which has one of a glycidyl ether functional group, a ring-opened glycidyl ether functional group and an oxythane functional group, and one of a phenol novolac resin-based backbone, a bisphenol-A-based backbone, a bisphenol-F-based backbone, and an alicyclic-based backbone; a cationic photo initiator; a solvent; and an adhesion promoter.
The prepolymer included in the first and second negative photoresist compositions may be cross-linked when exposed to actinic radiation.
The prepolymer may be formed from a backbone monomer selected from the group consisting of phenol, o-crezole, ρ-crezole, bisphenol-A, an alicyclic compound, and a mixture thereof.
A prepolymer having the glycidyl ether functional group may be, but is not limited to, a prepolymer having a di-functional glycidyl ether functional group or a prepolymer having a multi-functional glycidyl ether functional group. These prepolymers will now be described in detail. First, the prepolymer having a di-functional glycidyl ether functional group may be a compound represented by Formula 1.
where m is an integer ranging from 1 to 20.
The prepolymer having a di-functional glycidyl ether functional group may form a film having a low crosslinkage density.
Examples of the prepolymer having a di-functional glycidyl ether functional group are EPON 828, EPON 1004, EPON 1001F, and EPON 1010 which are produced by Shell Chemical Co., Ltd; DER-332, DER-331, and DER-164 which are produced by Dow Chemical Co., Ltd; and ERL-4201 and ERL-4289 which are produced by Union Carbide Co., Ltd. However, the prepolymer having a di-functional glycidyl ether functional group is not limited to these products.
Examples of the prepolymer having a multi-functional glycidyl ether functional group are EPON SU-8 and EPON DPS-164 which are produced by Shell Chemical Co., Ltd; DEN-431 and DEN-439 which are produced by Dow Chemical Co., Ltd; and EHPE-3150 which is produced by Daicel Chemical Co., Ltd. However, the prepolymer having a multi-functional glycidyl ether functional group is not limited to these products.
In the prepolymer having a monomer repeating unit which has a glycidyl ether functional group and a phenol novolac resin-based backbone, a backbone monomer suitable for the phenol novolac resin may be phenol. The obtained compound may be represented by Formula 2.
where n is an integer ranging from about 1 to 20, and specifically, from 1 to 10.
In the prepolymer having a monomer repeating unit which has a glycidyl ether functional group and a phenol novolac resin-based backbone, a backbone monomer suitable for the phenol novolac resin may also be a branched phenol, such as o-crezole or ρ-crezole. The obtained prepolymer may be represented by Formulae 3 or 4.
where n is an integer ranging from about 1 to 20, and specifically, from 1 to 10.
In the prepolymer having a monomer repeating unit which has a glycidyl ether functional group and a bisphenol-A-based backbone, a backbone monomer suitable for the phenol novolac resin may be bisphenol A. The obtained compound may be represented by Formulae 5 and 6:
where n is an integer ranging from about 1 to 20, and specifically, from 1 to 10.
The prepolymer having a monomer repeating unit which has a glycidyl ether functional group and an alicyclic-based backbone may be represented by Formula 7. Specifically, examples of the prepolymer having a monomer repeating unit which has a glycidyl ether functional group and an alicyclic-based backbone are addition products of 1,2-epoxy-4(2-oxiranyl)-cyclohexane of 2,2-bis(hydroxy methyl)-1-butanol (product name: EHPH-3150]:
where n is an integer ranging from about 1 to 20, and specifically, from 1 to 10.
The prepolymer having a monomer repeating unit which has a glycidyl ether functional group and a bisphenol-F-based backbone may be represented by Formula 8:
where n is an integer ranging from about 1 to 20, and specifically, from 1 to 10.
The prepolymer having a monomer repeating unit which has an oxythane functional group and a bisphenol-A-based backbone may be represented by Formula 9:
where n is an integer ranging from about 1 to 20, and specifically, from 1 to 10.
The prepolymer may include at least one compounds selected from the group consisting of the compounds represented by Formulae 1 to 9.
The cationic photo initiator included in each of the first and second negative photoresist compositions used in the present general inventive concept may be any material that generates an ion or a free radical that initiates a polymerization reaction when exposed to light. For example, such a material may be an aromatic halonium or sulfonium salt of Group VA or VI elements, such as UVI-6974 produced by Union Carbide Co. or SP-172 produced by Asahi denka.
The aromatic sulfonium salt may be triphenylsulfonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate (UVI-6974), phenylmethylbenzylsulfonium hexafluoroantimonate, phenylmethylbenzylsulfonium hexafluorophosphate, triphenylsulfonium hexafluorophosphate, methyl diphenylsulfonium tetrafluoroborate, or dimethyl phenylsulfonium hexafluorophosphate.
The aromatic halonium salt may be an aromatic iodonium salt. The aromatic iodonium salt may be, but is not limited to, diphenyliodonium tetrafluoroborate, diphenyliodonium hexafluoroantimonate, or butylphenyliodonium hexafluoroantimonate (SP-172).
The amount of the cationic photo initiator may be in a range of 1 to 10 parts by weight, specifically, 1.5 to 5 parts by weight, based on 100 parts by weight of the prepolymer. When the amount of the cationic photo initiator is less than 1 part by weight, a cross-linking reaction may insufficiently occur; alternatively, when the amount of the cationic photo initiator is greater than 10 parts by weight, a higher amount of light energy than light energy appropriate to a layer thickness is required, which thereby reduces the cross-linking speed.
The solvent included in each of the first and second negative photoresist compositions used in the present general inventive concept may include at least one compound selected from the group consisting of gamma-butyrolactone, propylene glycol methyl ethyl acetate, tetrahydrofurane, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and xylene.
The amount of the solvent may be in a range of 30 to 300 parts by weight, specifically, 50 to 200 parts by weight based on 100 parts by weight of the prepolymer. When the amount of the solvent is less than 30 parts by weight, the viscosity of the obtained polymer may be increased and processability may be degraded. Alternatively, when the amount of the solvent is greater than 300 parts by weight, the viscosity of the obtained polymer may be decreased and thus it may be difficult to form a pattern.
The adhesion promoter included in each of the first and second negative photoresist compositions used in the present general inventive concept may be represented by Formula 11.
where R1, R2, R3 and R4 are each independently, hydrogen, halogen atom, a carboxyl group, an amino group, a nitro group, a cyano group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C1-C20 heteroalkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C7-C30 arylalkyl group, a substituted or unsubstituted C5-C30 heteroaryl group, or a substituted or unsubstituted C3-C30 heteroarylalkyl group.
The adhesion promoter may be, but is not limited to, glycidoxypropyltrimethoxysilane, glycidoxypropylmethyldimethoxysilane, glycidoxypropyldimethylethoxysilane mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, or N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.
The amount of the adhesion promoter may be in a range of 1 to 15 parts by weight, specifically, 5 to 10 parts by weight, based on 100 parts by weight of the prepolymer. When the amount of the adhesion promoter is less than 1 part by weight, the adhesion promoter may have little effect. Alternatively, when the amount of the adhesion promoter is greater than 15 parts by weight, the crosslinking density of the prepolymer may be lowered.
Each of the first and second negative photoresist compositions may further include other additives, such as a photo-accelerator, a silane coupling agent, a filler, a viscosity controller, a humidifier, or a photo stabilizer. The amount of such respective additives may be in a range of 0.1 to 20 parts by weight based on 100 parts by weight of the prepolymer.
The photo-accelerator may absorb light energy enabling easy energy delivery to another compound, which can be used to generate radical or ion initiators. The photo-accelerator may widen a wavelength range suitable for exposure. In general, the photo-accelerator may be an optical absorption chromophore included in an aromatic group. Also, the photo-accelerator may induce formation of a photo initiator which generates radicals or ions.
The terminology of “alkyl group” used in the present general inventive concept may refer to a linear or branched C1-C20 alkyl group including, for example, a linear or branched C1-C12 alkyl group, such as a linear or branched C1-C6 alkyl group. Such unsubstituted alkyl group may be methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, pentyl, isoamyl, or hexyl. One or more hydrogen atoms included in such alkyl group may be substituted with a halogen atom, a hydroxyl group, —SH, a nitro group,
a cyano group, a substituted or unsubstituted amino group, such as —NH2, —NH(R), or —N(R′)(R″) where R′ and R″ are each independently C1-C10 alkyl group, an amidino group, a hydrazine group, a hydrazone group, a carboxyl group, a sulfonic acid group, a phosphoric acid group, a C1-C20 alkyl group, a C1-C20 halogenated alkyl group, a C1-C20 alkenyl group, a C1-C20 alkynyl group, a C1-C20 heteroalkyl group, a C6-C20 aryl group, a C6-C20 arylalkyl group, a C6-C20 heteroaryl group, or a C6-C20 heteroarylalkyl group.
The term “alkoxy group” used in the present general inventive concept may refer to an oxygen-containing linear or branched alkoxy group having a C1-C20 alkyl moiety. The alkoxy group may include one to six carbon atoms, specifically, one to three carbon atoms. Examples of the alkoxy group are methoxy, ethoxy, propoxy, butoxy, and t-butoxy The alkoxy group may be further substituted with one or more halogen atoms, such as F, Cl, or Br to form a haloalkoxy group. Examples of the haloalkoxy group are fluoromethoxy, chloromethoxy, trifluoromethoxy, trifluoroethoxy, fluoroethoxy, and fluoropropoxy. One or more hydrogen atoms of the alkoxy group may be substituted with the substituents which have been described with reference to the alkyl group.
The term “alkenyl group” used in the present general inventive concept may refer to a linear or branched C2-C20 aliphatic hydrocarbon having a C—C double bond. A suitable alkenyl group may include 2 to 12 carbon atoms in a chain thereof, such as, for example, 2 to 6 carbon atoms in the chain thereof. Branched C2-C20 aliphatic hydrocarbon having a C—C double bond refers to a linear alkenyl chain to which one or more low alkyl or low alkenyl group are attached. Such an alkenyl group may not be substituted, or independently substituted with one or more groups selected from the group consisting of halo, carboxy, hydroxy, formyl, sulfur, sulfino, carbamoyl, amino and imino. In this regard, the substituent of the alkenyl group may not be limited to these groups. Such an alkenyl group may be ethenyl, prophenyl, carboxyethenyl, carboxyprophenyl, sulfinoethenyl or sulfonoethenyl. One or more hydrogen atoms of the alkenyl group may be substituted with the substituents which have been described with reference to the alkyl group.
The term “alkynyl group” used in the present general inventive concept may refer to a linear or branched C2-C20 aliphatic hydrocarbon group having a C—C triple bond. A suitable alkynyl group may include 2 to 12 carbon atoms in a chain thereof, such as, for example, 2 to 6 carbon atoms in the chain thereof. Branched C2-C20aliphatic hydrocarbon group having a C—C triple bond may refer to a linear alkynyl chain to which one or more low alkyl or low alkynyl groups are attached. Such an alkynyl group may not be substituted, or independently substituted with one or more groups selected from the group consisting of halo, carboxy, hydroxy, formyl, sulfur, sulfino, carbamoyl, amino and imino. In this regard, the substituents of the low alkenyl groups may not be limited to those groups. One or more hydrogen atoms of the alkynyl group may be substituted with the substituents which have been described with reference to the alkyl group.
The term “heteroalkyl group” used in the present general inventive concept may refer to a functional group in which a back bone of the alkyl group includes a hetero atom, such as N, O, P, or S. In this regard, the back bone of the alkyl group may include 1-20 carbons including, for example, 1-12 carbons, such as 1-6 carbons. One or more hydrogen atoms of the heteroalkyl group may be substituted with the substituents which have been described with reference to the alkyl group.
The term “aryl group” used in the present general inventive concept may refer to a C6-C30 carbocyclic aromatic system having one or more rings in which the rings are used alone or in combination. The rings may be attached or fused together using a pendent method. The term “aryl” refers to an aromatic radical, such as phenyl, naphthyl, tetrahydronaphthyl, indan, or biphenyl. For example, the aryl may be phenyl. One or more hydrogen atoms of the aryl group may be substituted with the substituents which have been described with reference to the alkyl group.
The term “arylalkyl group” used in the present general inventive concept may refer to an alkyl group that has one or more hydrogen atoms substituted with the aryl group.
The term “heteroaryl group” used in the present general inventive concept may refer to a monovalent monocyclic or the bicyclic aromatic radical having 5-30 ring atoms which consist of one, two, or three hetero atoms selected from N, O, and S, and carbons. In addition, the term refers to a monovalent cyclic or the bicyclic aromatic radical which forms, for example, N-oxide or a quaternary salt through oxidation or quanternization of a hetero atom in a chain thereof. Examples of the heteroaryl group are thienyl, benzothienyl, pyridyl, pyrazinyl, pyrimidinyl, pyridazinyl, quinolinyl, quinoxalinyl, imidazolyl, puranyl, benzopuranyl, thiazolyl, isoxazoline, benzisoxazoline, benzimidazolyl, triazolyl, pyrazolyl, pyrrolyl, indolyl, 2-pyridonyl, N-alkyl-2-pyridonyl, pyrazinonyl, pyridazinonyl, pyrimidinonyl, oxazolonyl, N-oxdies corresponding thereto, such as pyridyl N-oxide, quinolinyl N-oxide, and a quaternary salt thereof. One or more hydrogen atoms of the heteroaryl group may be substituted with the substituents which have been described with reference to the alkyl group.
The term “heteroarylalkyl group” used in the present general inventive concept may refer to a functional group prepared by substituting one or more hydrogen atom with the defined heteroaryl group. Specifically, the heteroarylalkyl group may refer to a C3 to C30 carbocycle aromatic system. One or more hydrogen atoms of the heteroarylalkyl group may be substituted with the substituents which have been described with reference to the alkyl group.
A method of manufacturing an inkjet printhead according to the present general inventive concept will now be described in detail. The method includes forming a heater to heat ink, and an electrode to supply a current to the heater, on a substrate; forming a channel forming layer to define an ink channel by coating a first negative photoresist composition on the substrate on which the heater and the electrode are formed and then patterning the coated composition using a photolithography process; forming a sacrificial layer on the substrate on which the channel forming layer is formed such that the sacrificial layer covers the channel forming layer; planarizing top surfaces of the channel forming layer and sacrificial layer using a polishing process; forming a nozzle layer having a nozzle by coating a second negative photoresist composition on the channel forming layer and the sacrificial layer and patterning the coated composition using a photolithography process; forming an ink feed hole in the substrate; and removing the sacrificial layer, wherein the first and second negative photoresist compositions may be the same or different from each other, and each of the first and second negative photoresist compositions includes a prepolymer having a monomer repeating unit which has one of a glycidyl ether functional group, a ring-opened glycidyl ether functional group and an oxythane functional group, and one of phenol novolac resin-based backbone, bisphenol-A-based backbone, bisphenol-F-based backbone, and alicyclic -based backbone; a cationic photo initiator; a solvent; and an adhesion promoter.
In the method, the substrate may be a silicon wafer.
In the method, the forming of a channel forming layer may include completely coating a first negative photoresist composition on a surface of the substrate to form a first photoresist layer; exposing the first photoresist layer using a first photomask having an ink channel pattern; and developing the first photoresist layer to remove the unexposed portion of the first photoresist layer so as to form the channel forming layer.
In the method, a glue layer to enhance an adhesive force between the substrate and the channel forming layer is not formed. That is, the channel forming layer is directly formed on the substrate. The method does not use a glue layer because a negative photoresist composition that is used to form the channel forming layer includes an adhesion promoter to improve an adhesive force of the channel forming layer with respect to the substrate. As a result, there is no need to coat the glue layer on the substrate, to form a mask to form a pattern, and to etch the glue layer. Thus, the manufacturing process can be simplified, and the manufacturing costs can be decreased.
In the method, the sacrificial layer may include a positive photoresist or a non-photosensitive soluble polymer. The positive photoresist may be imide-based positive photoresist, and the non-photosensitive soluble polymer may include at least one resin selected from the group consisting of phenol resin, poly urethane resin, epoxy resin, poly imide resin, acryl resin, poly amid resin, urea resin, melamine resin, and silicon resin. In this regard, the term ‘soluble’ refers to solubility with respect to a specific solvent.
In the forming of the sacrificial layer of the method, the sacrificial layer may be formed to have a greater thickness than the channel forming layer. The sacrificial layer may be formed by spin coating.
In the planarizing of the method, top portions of the channel forming layer and sacrificial layer may be planarized using a polishing process until the ink channel has a predetermined height. The polishing process may be a chemical-mechanical-polishing (CMP) process.
In the method, the forming of a nozzle layer may include coating the second negative photoresist composition on the channel forming layer and the sacrificial layer to form a second photoresist layer; exposing the second photoresist layer using a second photomask having a nozzle pattern; and developing the second photoresist layer to remove unexposed portions of the second photoresist layer so as to form a nozzle and a nozzle layer.
The forming of an ink feed hole may include coating photoresist on a bottom surface of the substrate; patterning the photoresist to form an etch mask to form the ink feed hole; and etching portions of the bottom surface of the substrate that are exposed through the etch mask to form the ink feed hole. In this regard, the bottom surface of the substrate may be etched using a dry etching method using plasma or a wet etching method using tetramethyl ammonium hydroxide (TMAH) or KOH as an etchant.
According to the present general inventive concept, a top surface of a sacrificial layer may be planarized and thus, a shape and dimensions of an ink channel may be easily controlled, and thus, uniformity of the ink channel can be improved.
Referring to
Specifically, the heater 141 is formed by depositing a resistance pyrogenic substance, such as a tantalum-nitride alloy or a tantalum-aluminum alloy, on the substrate 110 by using a sputtering method or a chemical vapor deposition method and then patterning the deposited material.
The electrode 142 is formed by depositing a conductive metal, such as aluminum or aluminum alloy, on the substrate 110 by using a sputtering method and then patterning the deposited material. Also, although not illustrated, a protective layer formed of silicon oxide or a silicon nitride may be formed on the heater 141 and the electrode 142.
Then, referring to
Then, referring to
Then, the first negative photoresist layer 121 is developed to remove the unexposed portion of the first negative photoresist layer 121 so as to form the channel forming layer 120 to define an ink channel, as illustrated in
Then, referring to
Then, referring to
Then, referring to
The second negative photoresist layer 131 is used to form the nozzle layer 130 (refer to
In addition, since the top surfaces of the sacrificial layer S and the channel forming layer 120 are planarized to be flush with each other in the previous process, deformation or melting of an edge portion of the sacrificial layer S due to a reaction between a material forming the second negative photoresist layer 131 and a material forming the sacrificial layer S may not occur. Therefore, the second photoresist layer 131 can be adhered to the top surface of the channel forming layer 120.
Then, referring to
Then, referring to
Then, referring to
The present general inventive concept will be described in further detail with reference to the following examples. These examples are for illustrative purposes only and are not intended to limit the scope of the present general inventive concept.
PREPARATION EXAMPLE 1 Preparation of Negative Photoresist Composition30 g of xylene (produced by Samchun Chemical Co.), 2 g of glycidoxypropyltrimethoxysilane (produced by Sigma-Aldrich), and 2 g of SP-172 (produced by Asahi Denka Korea Chemical Co.) were added to a jar to prepare a resist solution. Then, 40 g of EPON SU-8 (produced by Shell Chemical Co.) was added to the jar, and then the resultant solution was mixed using an impeller for about 24 hours, thereby preparing a negative photoresist composition.
EXAMPLE 1A tantalum nitride heater pattern 141 having a thickness of about 500 Å and an electrode pattern 142 formed of an AlSiCu alloy (Si and Cu each in an amount of 1 wt. % or less) having a thickness of about 500 Å were formed on a 6-inch silicon wafer 110 using a conventional sputtering process and a photolithography process (see
Then, as illustrated in
Then, as illustrated in
Then, a CMP process was performed to planarize top surfaces of the channel forming layer 120 and the sacrificial layer S, as illustrated in
The negative photoresist composition prepared according to Preparation Example 1 and a second photomask 163 were used to form a nozzle layer pattern 130 on the silicon wafer 110 on which the channel forming layer 120 and the sacrificial layer S were formed using the same conditions as when the channel forming layer 120 was formed (see
As illustrated in
Finally, the wafer was dipped in a methyl lactate solvent for 2 hours to remove the sacrificial layer S and thereby form an ink chamber 153 and a restrictor 152 as defined by the channel forming layer 120 (see
As described above, an inkjet printhead was manufactured using the negative photoresist composition prepared according to Preparation Example 1 as the first negative photoresist composition and the second negative photoresist composition.
Referring the dotted lines of
While the present general inventive concept has been particularly illustrated and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present general inventive concept as defined by the following claims.
Claims
1. A method of manufacturing an inkjet printhead, the method comprising:
- forming, on a substrate, a heater to heat ink, and an electrode to supply a current to the heater;
- forming a channel forming layer to define an ink channel by coating a first negative photoresist composition on the substrate on which the heater and the electrode are formed and then patterning the coated composition using a photolithography process;
- forming a sacrificial layer on the substrate on which the channel forming layer is formed such that the sacrificial layer covers the channel forming layer;
- planarizing top surfaces of the channel forming layer and sacrificial layer using a polishing process;
- forming a nozzle layer having a nozzle by coating a second negative photoresist composition on the channel forming layer and the sacrificial layer and patterning the coated composition using a photolithography process;
- forming an ink feed hole in the substrate; and
- removing the sacrificial layer,
- wherein each of the first and second negative photoresist compositions comprises:
- a prepolymer having a monomer repeating unit which has one of a glycidyl ether functional group, a ring-opened glycidyl ether functional group and an oxythane functional group, and one of phenol novolac resin-based backbone, bisphenol-A-based backbone, bisphenol-F-based backbone, and alicyclic backbone;
- a cationic photo initiator;
- a solvent; and
- an adhesion promoter.
2. The method of claim 1, wherein the polishing process is a chemical mechanical polishing (CMP) process.
3. The method of claim 1, wherein the substrate comprises:
- a silicon wafer.
4. The method of claim 1, wherein the forming of the channel forming layer comprises:
- completely coating the first negative photoresist composition on a surface of the substrate to form a first photoresist layer;
- exposing the first photoresist layer using a first photomask having an ink channel pattern; and
- developing the first photoresist layer to remove the unexposed portion of the first photoresist layer so as to form the channel forming layer.
5. The method of claim 1, wherein the sacrificial layer comprises:
- a positive photoresist or a non-photosensitive soluble polymer.
6. The method of claim 1, wherein the positive photoresist is an imide-based positive photoresist.
7. The method of claim 5, wherein the non-photosensitive soluble polymer comprises:
- at least one resin selected from the group consisting of phenol resin, poly urethane resin, epoxy resin, poly imide resin, acryl resin, poly amid resin, urea resin, melamine resin, and silicon resin.
8. The method of claim 1, wherein, in the forming of the sacrificial layer, the sacrificial layer is formed to have a greater thickness than the channel forming layer.
9. The method of claim 1, wherein, in the forming of the sacrificial layer, the sacrificial layer is formed by spin coating.
10. The method of claim 1, wherein, in the planarizing, the top surfaces of the channel forming layer and the sacrificial layer are polished until the ink channel has a predetermined height.
11. The method of claim 1, wherein the forming the nozzle layer comprises:
- coating the second negative photoresist composition on the channel forming layer and the sacrificial layer to form a second photoresist layer;
- exposing the second photoresist layer using a second photomask having a nozzle pattern; and
- developing the second photoresist layer to remove an unexposed portion of the second photoresist layer so as to form a nozzle and a nozzle layer.
12. The method of claim 1, wherein the forming of the ink feed hole comprises:
- coating photoresist on a bottom surface of the substrate;
- patterning the photoresist to form an etch mask that is used to form the ink feed hole; and
- etching a portion of the bottom surface of the substrate that is exposed by the etch mask so as to form an ink feed hole.
13. The method of claim 12, wherein the bottom surface of the substrate is dry-etched using plasma.
14. The method of claim 12, wherein the bottom surface of the substrate is wet-etched using tetramethyl ammonium hydroxide (TMAH) or KOH as an etchant.
15. The method of claim 1, wherein each of the first and second negative photoresist compositions comprises:
- 1 to 10 parts by weight of the cationic photo initiator, 30 to 300 parts by weight of the solvent, and 1 to 15 parts by weight of the adhesion promoter, based on 100 parts by weight of the prepolymer.
16. The method of claim 1, wherein the prepolymer is formed from a backbone monomer selected from the group consisting of phenol, o-crezole, p-crezole, bisphenol-A, an alicyclic compound, and a mixture thereof.
17. The method of claim 1, wherein the prepolymer comprises:
- one or more compounds selected from the group consisting of compounds represented by Formulae 1 to 9:
- where m is an integer ranging from 1 to 20, and n is an integer ranging from 1 to 20.
18. The method of claim 1, wherein the cationic photo initiator may be sulfonium salt or iodonium salt.
19. The method of claim 1, wherein the solvent comprises:
- at least one compound selected from the group consisting of γ-butyrolactone, propylene glycol methyl ethyl acetate (PGMEA), tetrahydrofurane (THF), methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and a mixture thereof.
20. The method of claim 1, wherein the adhesion promoter is represented by Formula 10:
- where R1, R2, R3 and R4 are each independently, hydrogen, halogen atom, a carboxyl group, an amino group, a nitro group, a cyano group, a substituted or unsubstituted C1-C20 alkyl group, a substituted or unsubstituted C1-C20 alkoxy group, a substituted or unsubstituted C2-C20 alkenyl group, a substituted or unsubstituted C2-C20 alkynyl group, a substituted or unsubstituted C1-C20 heteroalkyl group, a substituted or unsubstituted C6-C30 aryl group, a substituted or unsubstituted C7-C30 arylalkyl group, a substituted or unsubstituted C5-C30 heteroaryl group, or a substituted or unsubstituted C3-C30 heteroarylalkyl group.
21. The method of claim 1, wherein the adhesion promoter comprises:
- at least one compound selected from the group consisting of glycidoxypropyltrimethoxysilane, glycidoxypropylmethyldimethoxysilane, glycidoxypropyldimethylethoxysilane mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane.
22. An inkjet printhead, comprising:
- a substrate; and
- a channel forming layer directly formed on the substrate without a glue layer formed therebetween,
- wherein a negative photoresist composition having an adhesion promoter to improve an adhesive force of the channel forming layer with respect to the substrate is used to form the channel forming layer.
23. A method of manufacturing an inkjet printhead, the method comprising:
- forming a channel forming layer on a substrate to define an ink channel by coating a first negative photoresist composition on the substrate; and
- forming a nozzle layer having a nozzle by coating a second negative photoresist composition on the channel forming layer,
- wherein each of the first and second negative photoresist compositions includes an adhesive promoter so that a glue layer is not used between the substrate and the channel forming layer.
Type: Application
Filed: Aug 18, 2008
Publication Date: Mar 19, 2009
Applicant: Samsung Electronics Co., Ltd. (Suwon-si)
Inventors: Byung-ha PARK (Suwon-si), Young-ung Ha (Suwon-si), Sung-joon Park (Suwon-si), Jeong-wuk Han (Suwon-si)
Application Number: 12/193,086
International Classification: B44C 1/22 (20060101); B41J 2/04 (20060101);